xfs: make sure xfs_sync_fsdata covers the log

We want to always cover the log after writing out the superblock, and
in case of a synchronous writeout make sure we actually wait for the
log to be covered.  That way a filesystem that has been sync()ed can
be considered clean by log recovery.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Alex Elder <aelder@sgi.com>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 21 insertions, 7 deletions

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 7647b8db3ca3..961df0a22c78 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -309,11 +309,15 @@ xfs_sync_attr(
 STATIC int
 xfs_commit_dummy_trans(
         struct xfs_mount        *mp,
-        uint                    log_flags)
+        uint                    flags)
 {
         struct xfs_inode        *ip = mp->m_rootip;
         struct xfs_trans        *tp;
         int                     error;
+        int                     log_flags = XFS_LOG_FORCE;
+
+        if (flags & SYNC_WAIT)
+                log_flags |= XFS_LOG_SYNC;
 
         /*
          * Put a dummy transaction in the log to tell recovery
@@ -331,13 +335,12 @@ xfs_commit_dummy_trans(
         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
         xfs_trans_ihold(tp, ip);
         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
-        /* XXX(hch): ignoring the error here.. */
         error = xfs_trans_commit(tp, 0);
-
         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 
+        /* the log force ensures this transaction is pushed to disk */
         xfs_log_force(mp, 0, log_flags);
-        return 0;
+        return error;
 }
 
 int
@@ -385,7 +388,20 @@ xfs_sync_fsdata(
         else
                 XFS_BUF_ASYNC(bp);
 
-        return xfs_bwrite(mp, bp);
+        error = xfs_bwrite(mp, bp);
+        if (error)
+                return error;
+
+        /*
+         * If this is a data integrity sync make sure all pending buffers
+         * are flushed out for the log coverage check below.
+         */
+        if (flags & SYNC_WAIT)
+                xfs_flush_buftarg(mp->m_ddev_targp, 1);
+
+        if (xfs_log_need_covered(mp))
+                error = xfs_commit_dummy_trans(mp, flags);
+        return error;
 
  out_brelse:
         xfs_buf_relse(bp);
@@ -572,8 +588,6 @@ xfs_sync_worker(
                 /* dgc: errors ignored here */
                 error = xfs_qm_sync(mp, SYNC_TRYLOCK);
                 error = xfs_sync_fsdata(mp, SYNC_TRYLOCK);
-                if (xfs_log_need_covered(mp))
-                        error = xfs_commit_dummy_trans(mp, XFS_LOG_FORCE);
         }
         mp->m_sync_seq++;
         wake_up(&mp->m_wait_single_sync_task);